If you take supplements to help enhance your health, you want to ensure those you take are working as effectively as possible. That’s especially true for a supplement as vital as magnesium an essential mineral that the body depends on to function. To optimize your magnesium intake, you must first understand how it works and how long it stays in your body.
Why is magnesium important for your health?
What exactly is magnesium? Magnesium is the fourth most abundant mineral in the body and is involved in more than 300 different biochemical reactions, including:
- Nerve and muscle function
- Immune system health
- Regulating pressure and blood glucose levels
- Producing energy and protein
- Keeping bones strong
- Kidney function
- Gastrointestinal health
Magnesium is naturally found in many foods like dairy products, fruits, nuts, and legumes. Most people get enough of it in their diet for the body to perform regular functions; however, it’s still common to have low levels.
An estimated 43% of adults in the U.S. are unable to meet daily magnesium recommendations through diet alone, hence the reason magnesium supplements are widely recommended.
What are the different types of magnesium?
Not all magnesium is created equal. Different forms of magnesium are available, and some are more beneficial to your health than others.
These are just a few of the types of magnesium found in food and supplements:
- Magnesium citrate is found naturally in citrus fruits and is bound with citric acid.
- Magnesium glycinate is made by combining the amino acid glycine with magnesium.
- Magnesium lactate is made by combining lactic acid and magnesium.
- Magnesium malate is made by combining malic acid and magnesium.
- Magnesium chloride is a magnesium salt that contains chlorine.
- Magnesium oxide, a white powdery substance, is a salt made from oxygen and magnesium.
These various forms of magnesium serve different functions in food, but some are better than others when taken as a supplement. Magnesium glycinate, citrate, malate, lactate, and chloride tend to be better absorbed and more bioavailable, meaning your body can use the supplement more efficiently than magnesium oxide and sulfate. (Bioavailability refers to the fraction of a substance that actually reaches your circulation so that your body can use it.)
Keep in mind that certain forms of magnesium are used as laxatives. For example, magnesium citrate and magnesium hydroxide (found in PediaLax and Milk of Magnesia) are used to treat occasional constipation.
What causes low magnesium levels?
Certain disorders and underlying conditions are associated with low magnesium levels and may require magnesium supplementation beyond food sources. Examples include:
- Alcohol use disorder
- Gastrointestinal disease
- Kidney disease
- Type 2 diabetes
- Thyroid disorders
Other factors can also affect magnesium levels, such as older age and taking certain supplements or medications. Taking high doses of zinc in supplements, for example, can reduce magnesium absorption, leading to lower levels in the body.
How do you know if your body is not absorbing magnesium? Although rare, people who are truly magnesium deficient may experience symptoms like sleepiness, muscle weakness, nausea and vomiting, loss of appetite, and hyperexcitability. A moderate or severe deficiency can lead to seizures, abnormal heart rhythms, and low blood potassium and calcium levels.
How long does magnesium stay in the body?
You might think the body contains massive stores of magnesium since it’s such a vital nutrient. That is partially true.
Yes, magnesium is stored in the body; however, most of that, 50–60%, is in bones and other tissues, not the blood. The remaining magnesium you ingest daily is absorbed, utilized, and released relatively quickly throughout 12 to 24 hours. The kidneys regulate magnesium levels and excrete about 120 mg of magnesium through your urine every day.
This process slows when people have low magnesium levels, but it’s typically recommended that people take magnesium daily. The kidneys' ability to regulate magnesium levels is one of the reasons that it’s difficult to overdose on the mineral – they typically release excess magnesium within a day.
How long does it take for magnesium to be absorbed? Forms of magnesium that can be dissolved into a liquid tend to be more readily absorbed by the gut. Around 80% of oral magnesium is absorbed within 6–7 hours of ingesting.
Wondering how long it will take for your magnesium supplement to work? Most people notice a difference within a week, but it depends on your body and what you take it for.
What impacts how long magnesium stays in your body?
Diet plays a role in magnesium absorption. People who consume higher levels of protein and fructose seem to absorb more magnesium. Another factor is the form of magnesium consumed and how magnesium deficient you are.
While these things affect how fast magnesium is absorbed into the body, kidney health is the factor that plays the greatest role in how long it stays there. This is because your kidneys regulate how much magnesium your body can hold. People with kidney disease, often stemming from Type 2 Diabetes, are more likely to have magnesium dysregulation.
How to optimize your magnesium intake
So, how do you incorporate magnesium into your wellness routine? First is knowing how much to take.
Experts recommend adult males take 400 to 420 milligrams daily, while adult females take 310 to 320. Those who are pregnant should take 350–400 milligrams per day, and those lactating take 310–360 milligrams.
Your next step is choosing the right kind to take. Magnesium lactate may cause fewer gastrointestinal side effects and can be suitable for those who have difficulty taking other forms of magnesium. Magnesium citrate and malate are also good choices for most people because they tend to be more bioavailable and are helpful for constipation.
Best time to take magnesium
Is there the best time of day to take magnesium? Most experts say no. What’s most important is that you can find a schedule that works for you. Some say taking magnesium at night helps them sleep and wind down from the day; however, there isn’t conclusive evidence to back this.
Do you need to take magnesium with food? No, magnesium will absorb on an empty stomach, but people who experience gastrointestinal side effects may want to take it with food.
Who shouldn't take magnesium supplements?
People with underlying health conditions like heart disease, gastrointestinal disorders, diabetes, and kidney damage should talk to their healthcare providers before taking magnesium.
While it’s important to take a form of magnesium that’s absorbed well by your body, the type of magnesium doesn’t seem to affect how long it stays in your body. What’s more essential is whether you have any underlying health disorders affecting your body’s ability to absorb, utilize, and release magnesium.
What happens if you take magnesium for too long?
It depends on how much magnesium you take and whether you have a magnesium deficiency. Common side effects may include gastrointestinal upset, such as diarrhea. It is best to consult a healthcare provider before taking a daily magnesium supplement for a long period of time. They can do a blood test to check your magnesium levels to help determine if continued supplementation may be beneficial for you.
What is the quickest way to get magnesium into your body?
The quickest way to get magnesium into the body is by taking a more readily bioavailable form, like magnesium malate or magnesium citrate.
Keep in mind, however, that magnesium citrate may cause gastrointestinal upset or diarrhea in some people. Magnesium citrate is an active ingredient in various over-the-counter laxative products.
Are there any side effects from taking magnesium?
Although uncommon, some people experience gastrointestinal side effects like nausea, diarrhea, and abdominal cramping. People with underlying health conditions, especially kidney disease, may be more likely to experience adverse effects from magnesium supplements and should first consult a healthcare provider.
Magnesium is a key mineral that helps with over 300 biochemical reactions in the body.
Magnesium is found in many foods, but most people are unable to meet daily requirements through diet alone.
There are a number of different types of magnesium, some of which have more bioavailability than others. (Bioavailability refers to the fraction of a substance that actually reaches your circulation so that your body can use it.)
All forms of magnesium tend to be absorbed, utilized, and released through urine within 24 hours.
- MedlinePlus. Magnesium in diet.
- National Institutes of Health. Magnesium Fact Sheet for Health Professionals.
- National Library of Medicine. The Importance of Magnesium in Clinical Healthcare.
- National Library of Medicine. Nutrition and magnesium absorption: a review.
- National Library of Medicine. Magnesium lactate in the treatment of Gitelman syndrome: patient-reported outcomes.
- MedlinePlus. Magnesium Citrate.